Myopia, or near-sightedness, affects up to 25% of the United States population and, in some parts of the world, up to 75% of the population. In the myopic eye, the shape of the eyeball is elongated and light rays entering the eye are focused in front of the retina. The conventional treatment for myopia is prescribing corrective lenses. However, the typical corrective lens does not prevent the progression of myopia.
A number of methods to retard myopia progression, especially in children, have been proposed. These methods include using multifocal lenses, using lenses into which aberration is introduced or which control aberrations, using off-axis power lenses, reshaping the cornea, exercising the eye, and using pharmacological therapies.
The use of multifocal lenses and those having aberrations have proved to be disadvantageous in that the lenses compromise the wearer's distance vision. The other methods too suffer from disadvantages including discomfort, as with the corneal reshaping, and undesirable side effects, as with the drug therapies.